The overall objective of this project is to determine the composition and role of specific glycolipids in immune effector cell function. Two major aspects will deal with: (1) Testing whether certain glycolipids can function as tumor-specific cell surface markers. We have defined the glycolipid gangliotriosyl ceramide (asialo GM2) as a potential tumor associated marker in two mouse cell lines and have demonstrated both in vivo and in vitro that anti-asialo GM2 specific antibody-dependent immune lytic functions can be directed to the tumor cells. Future experiments will be designed to develop antibody-independent cellular cytotoxicity specific for asialo GM2. (2) Defining glycolipid markers on immune system effector cells. We have recently described the glycolipid ganglio-N-tetraosylceramide (asialo GM1) as a marker for murine natural killer (NK) cells. In addition we are determining the chemical structures of glycolipids on NK-susceptible target cells to define the "target antigen" to which NK cells are directed. The next step will be to determine what role effector cell glycolipids play in lytic phenomena. A vital class of reagents for these studies are monoclonal anti-glycolipid antibodies produced by the hybridoma technique.